1. Field of the Invention
The present invention relates to power mechanisms for adjusting venetian blinds, and in particular, to mechanisms having controllers for controlling the blind adjustment.
2. Description of Related Art
The well known venetian blinds are used to adjust the amount of sunlight entering a room. These blinds are often adjusted according to a predetermined schedule. For example, one may wish to close the blinds during a part of the day when the sun produces unacceptable glare. Also, house plants placed near a window may have special sunlight requirements. For example, some plants can be hurt by strong direct sunlight. Therefore a scheduled daily adjustment of venetian blinds can prevent plant injury. Unfortunately, the plant owner will not always be available to adjust the venetian blind on a daily schedule.
Venetian blinds regulate incoming light by adjusting the angle of elevation of a plurality of parallel slats or louvers. The original designs adjusted the slat angle with pull cords, although more recent designs replaced the pull cords with a vertical adjustment rod. This adjustment rod can be spun on its axis to operate a mechanism atop the venetian blind that adjusts the angle of elevation of the slats or louvers in the blind.
U.S. Pat. Nos. 4,173,721; 4,610,294; and 4,958,112 have mechanisms that pull the adjusting cords of draperies or venetian blinds. These mechanisms are designed to work with cords and therefore would be unusable with a venetian blind employing an adjustment rod. These references employ timers to operate the cords according to a predetermined schedule. See also U.S. Pat. Nos. 1,187,381; 1,525,781; and 4,664,169.
Accordingly, there is a need for a mechanism to adjust the adjustment rod on venetian blinds.